Polycarbonates (PC) are synthetic thermoplastic resins derived from bisphenols and phosgenes, or their derivatives. They are linear polyesters of carbonic acid and can be formed from dihydroxy compounds and phosgene or carbonate diesters, or by ester interchange. Polymerization may be in melt, aqueous, interfacial, or in nonaqueous solution. Polycarbonates are a useful class of polymers having many desired properties. They are highly regarded for optical clarity and enhanced impact strength and ductility at room temperature or below.
It is known however that polymerization reactions, including those used to manufacture polycarbonates, may not proceed to completion in all instances thus leading to the presence of unreacted residual monomer in the polymeric material. Besides affecting polymer properties, the presence of residual monomers may also be of concern in terms of emerging regulatory compliance. Therefore, complete conversion of monomers is usually the desire of any polymer producer but is not always attainable. Additionally, when subjected to certain conditions, polycarbonates can undergo degradation reactions, such as hydrolytic or thermolytic degradation, resulting in the formation of hydrolysis and/or thermolysis degradants or reaction products. The resulting degradants commonly correspond chemically to the monomeric starting materials initially used to manufacture the polycarbonate and may also be of concern.
To that end, there remains a need in the art for thermoplastic polycarbonate compositions whose residual monomer content, if any, and whose hydrolytic degradation products exhibit certain beneficial characteristics. Desirable characteristics of such residual monomer or degradants include, among others, relatively little or even no estradiol binding activity.